Cold working of pipe elements, for example, impressing a circumferential groove in a pipe element to accept a mechanical pipe coupling, is advantageously accomplished using roll grooving machines having an inner roller which engages an inside surface of the pipe element and an outer roller which simultaneously engages an outside surface of the pipe element opposite to the inner roller. As the pipe is rotated about its longitudinal axis, often by driving the inner roller, the outer roller is progressively forced toward the inner roller. The rollers have surface profiles which are impressed onto the pipe element circumference as it rotates, thereby forming a circumferential groove.
There are various challenges which this technique faces if it is to cold work pipe elements with the required tolerances to the necessary precision. Most pressing are the difficulties associated with producing a groove of the desired radius (measured from the center of the pipe element bore to the floor of the groove) within a desired tolerance range. These considerations have resulted in complicated prior art devices which, for example, require actuators for forcing the rollers into engagement with the pipe element and the ability for the operator to adjust the roller travel to achieve the desired groove radius. Additionally, prior art roll grooving machines have low production rates, often requiring many revolutions of the pipe element to achieve a finished circumferential groove. There is clearly a need for devices, for example, those using cams, to cold work pipe elements which are simple yet produce results with less operator involvement.